The present disclosure is directed to systems and techniques that provide for desired transfer of radiation by using close packed arrangements of resonators having fractal shapes, i.e., “fractal cells.” Systems and techniques according to the present disclosure provide one or more surfaces that act or function as heat or power radiating surfaces for which at least a portion of the radiating surface includes or is composed of “fractal cells” (small fractal shapes) (as antennas or resonators) placed sufficiently closed close together to one another (e.g., less than 1/20 wavelength) so that a surface (plasmonic) wave causes near replication of current present in one fractal cell in an adjacent fractal cell. A fractal of such a fractal cell can be of any suitable fractal shape and may have two or more iterations. The fractal cells may lie on a flat or curved sheet or layer and be composed in layers for wide bandwidth or multibandwidth transmission. The area of a surface (e.g., sheet) and its number of fractals determines the gain relative to a single fractal cell. As each cell is fed plasmonicly rather than directly, ‘dead’ or covered or out of resonance cells do not alter the ability of the other cells to work. The boundary edges of the surface may be terminated resistively so as to not degrade the cell performance at the edges. These surfaces may be referred to as fractal plasmonic surfaces (FPS's) and can provide benefits for thermal management and/or power delivery.
Such a fractal plasmonic surface (FPS) may be used to transfer radiation, e.g., via evanescent wave transfer. In doing so such surfaces can be used to remove radiative power and/or heat from one location to another, or divert it to another location. Such surfaces may be used to essentially diffuse power delivered to a part of the FPS and dissipate and or distribute it to other specific parts or globally. Heat for example, may be dissipated in this way, or a power “hotspot” supplied or hit with localized power may have the power spread out or diverted to other desired locations, e.g., different areas of a related machine or structure. In some embodiments, a FPS on a closed or curved surface may act as a cloaking device to divert power (in a wavelength or frequency of interest) from one side of the device to the other. In other embodiments, a refrigeration or cooling effect may be induced by transferring heat away from a FPS.
Exemplary embodiments of the present disclosure can provide techniques, including systems and/or methods, for cloaking objects at certain wavelengths/frequencies or over certain wavelength/frequency ranges (bands). Such techniques can provide an effective electromagnetic lens and/or lensing effect for certain wavelengths/frequencies or over certain wavelength/frequency ranges (bands).
In some embodiments, the effects produced by such techniques can include cloaking or so-called invisibility of the object(s) at the noted wavelengths or bands. Representative frequencies of operation can include, but are not limited to, those over a range of 500 MHz to 1.3 GHz, though others may of course be realized. Operation at other frequencies, including for example those of visible light, infrared, ultraviolet, and as well as microwave EM radiation, e.g., K, Ka, X-bands, etc. may be realized, e.g., by appropriate scaling of dimensions and selection of shape of the resonator elements.
Exemplary embodiments of the present disclosure can include a novel arrangement of resonators in a lattice-like configuration. The arrangements can include resonators of several different sizes and/or geometries arranged so that each size or geometry (“grouping”) corresponds to a moderate or high quality factor, “Q,” (that is moderate or low bandwidth) response that resonates within a specific frequency range.
For exemplary embodiments, fractal resonators can be used for the resonators in such structures because of their control of passbands, and smaller sizes compared to non-fractal based resonators. Their benefit arises from a size standpoint because they can be used to shrink the resonator(s), while control of passbands can reduce or eliminates issues of harmonic passbands that would resonate at frequencies not desired.
Further embodiments of the present disclosure are directed to scatterer or scattering structures. Additional embodiments of the present disclosure are directed to structures/techniques for activating and/or deactivating cloaking structures. Further embodiments of the present disclosure are directed to wideband absorbers.
It should be understood that other embodiments of FPS systems and methods according to the present disclosure will become readily apparent to those skilled in the art from the following detailed description, wherein exemplary embodiments are shown and described by way of illustration. The systems and methods of the present disclosure are capable of other and different embodiments, and details of such are capable of modification in various other respects. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
While certain embodiments are depicted in the drawings, one skilled in the art will appreciate that the embodiments depicted are illustrative and that variations of those shown, as well as other embodiments described herein, may be envisioned and practiced within the scope of the present disclosure.